92 SPORE OF VESICULIFERA. [BOOK i. 



disposed in a reticulate manner. Some of the cells, however, 

 may be observed to be slightly inflated, and to contain a 

 larger amount of endochrome than the rest : in each of these 

 inflated cells a spore is subsequently formed, and in the fol- 

 lowing way: The endochrome, after attaining a certain 

 degree of density from an increase in its development, not 

 from any derived from a contiguous cell, moves towards one 

 end of its cell ; it (the endochrome) shortly becomes divided 

 into two very unequal portions, the larger and terminal one 

 of which becomes converted into the spore, and the smaller 

 portion is found to be separated from this by a single septum. 

 A process has, in reality, taken place analogous to the fissi- 

 parous division of the cell of Zygnema ; two cells have been 

 formed within the original one, but in the Vesiculifera one of 

 these new cells is the spore. This is a fact of considerable 

 physiological importance." 



The same observer found that in Vesiculifera'sequalis, the 

 process of the formation of the spore is similar. In that 

 species, however, he was able to trace the mode of develop- 

 ment of the two or three contiguous spores, which are some- 

 times to be seen in the filaments of this species. The first 

 spore is formed in the way he previously mentioned, and 

 arrives at considerable maturity before there is any appear- 

 ance of one, contiguous to it, being produced; but it may 

 then be seen that the smaller portion of endochrome, which 

 had been separated just previously to the first spore being 

 formed, and which then occupied but little space in the cell, 

 has become considerably increased in amount, an increase 

 having also taken place in the length of the cell ; at length 

 the process of division, &c., occurs as before, and a second 

 spore is formed adjoining the first. The formation of a third 

 spore involves a similar chain of phenomena. 



The spores of flowerless plants are usually regarded as dif- 

 fering from seeds in not germinating from any fixed point, 

 but from whatever part is exposed to moisture and darkness. 

 This, however, is denied by Mr. Valentine in the case of 

 Pilularia, " for it is quite certain in that instance that ger- 

 mination invariably takes place at a fixed spot, which may 

 be pointed out before germination has commenced. It is at 



